Skip to main content

Full text of "The Cambridge Natural History"

See other formats


i8o

EXTINCT XENARTHRA

form of scattered plates, small and not fused together. The
general aspect of the skull is decidedly Sloth-like. As in that
animal, the malar bone is bifid posteriorly, and between the
bifurcation is embraced the process of the squamosal. This latter

is thus more de-
veloped than in the
Sloth, but there is
no actual union be-
tween it and the
malar. The pre~
maxilla is small.
The lower jaw has
both coronoid and
ascending processes,
and is massive.
There are five teeth
on each side above,
and four on each
side below, as in the
Sloths. There are
the normal seven
cervical vertebrae and sixteen dorsals. The limbs are not long and
slender, but short and strong, the animal having been terrestrial. The
fore-feet were five-toed, of which the three inner toes had claws. The
hind-feet were only four-toed, and the two Inner only were clawed.
jScelidotherium is a genus which is a trifle smaller than the
last. It has only four properly-developed toes in the fore-foot,
the thumb being rudimentary; of these, the first two bear claws.
The hind-feet are also four-toed. Like Mylodon, SceUdotherium
is a Pleistocene genus.

Grlossotherium has a skull very much like the last two
genera; but it is remarkable for the fact that the nostrils instead
of being unprotected with bone anteriorly are there closed by a
plate of bone formed by the well-developed premaxillae, the
nostrils appearing at the sides, and giving the skull a curious
likeness to that of a Chelonian. From a series of recent and
most important observations it appears to be clear that this genus
ha$ survived into quite modern, times.1

1 Dr. Moreno and M>. A, Smith. "Woodward In JVoc. Zool. JSoc. 1899, p. 144 ;
-   -                               d, ii. 1899, p. 149.

FIG. 105.óMylodon, robustus.    (Bestoration, after Owen.)